Lampadioteuthis megaleia Berry, 1916

Introduction

L. megaleia is a small, colorful squid that differs from other lycoteuthids, among other characters, in the presence of a hectocotylus and a rostrum on the gladius.

Brief diagnosis:

A lycoteuthid...

• with four ocular photophores.
• with stalked photophore at base of each tentacle.

Characteristics

1. Arms
   1. Right ventral arm hectocotylized in males with enlarged protective membrane in mid-arm.
      

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      Figure. Oral view of hectocotylus of L. megaleia, 31 mm ML. Drawing from Young (1964, p. 449).

      

      Figure. Oral view of the hecotcotylized right arm IV of L. megaleia, central North Atlantic. Photograph by R. Young.

2. Head
   
   1. Beaks: Descriptions can be found here: Lower beak; upper beak.
      
      
3. Photophores.
   1. Ocular and tentacular photophores
      1. Four ocular organs: 3 ventral in a line, 1 lateral.
      2. Five tentacular organs, basal organ raised above stalk.
         

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         Figure. Ventral view on anterior portion of head and base of brachial crown of a 27 mm ML L. megaleia. Arrows point to stalks of basal tentacle photophores. Photograph by R. Young, R/V G. O. Sars, Mar-Eco cruise, central North Atlantic.

   2. Visceral photophores
      1. Circular anal photophores lie on either side of rectum.
      2. Branchial photophores, transversely elongate, each lies at base of one gill.
      3. Abdominal photophores absent.
      4. Postero-abdominal photophore, single, lies in medial line attached to inner surface of mantle and visceral mass.
         

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         Figure. Ventral view of the mantle of a damaged but fresh L. megaleia, 27 mm ML, showing the visceral photophores through the translucent muscle. The elongate right branchial photophore has a bluish region at one end. Photograph by R. Young, R/V G. O. Sars, Mar-Eco cruise, central North Atlantic.



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Figure. Ventral view of the mantle cavity of L. megaleia, preserved, central North Atlantic, showing visceral photophores. Left arrow - anal photophore. Middle arrow - branchial photophore. Right arrow - postero-abdominal photophore which was damaged while cutting open the mantle. Photograph by R. Young.


4. Pigmentation
   1. Squid with numerous functional chromatophores.
   2. External skin overlying photophores with violet pigment.
      

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      Figure. Ventro-lateral view of L. megaleia, same specimen as in title photograph. Note the violet patches on the mantle covering the posterior visceral photophores (skin over the anal photophores has been lost due to damage), the ocular photophores (damage has moved the skin away from some photophores) and the tentacular photophores.

5. Gladius
   1. Rostrum present.
      

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      Figure. Gladius of L. megaleia, 18.5 mm GL, USNM 727882. Upper left - Ventral view of posterior mantle and fins showing rostrum and conus of gladius. Lower right - Ventral view of gladius with cross-sections. Drawings from Toll (1982).

6. Viscera
   1. Single penis present in males.

Comments

Drawings of the tentacular club and the club and arm suckers can be found here.

The violet pigment overlying the photophores presumably acts as a color filter to allow the bioluminescence to more closely match the color of the downwelling sun or moonlight. The same type of "detached" filter appears to be present in the photophores of species of Lycoteuthis.

Life History

The small squid, 8 mm ML (an advanced paralarva ?), below is virtually a minature subadult in appearance except for some differences in body proportions, size of photophores and the absence of all but the large basal photophore on the tentacle. Note presence of this photophore at the base of the tentacle in the drawing (arrow).

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Figure. L. megaleia, 8 mm, ventral view. Drawing from Young, 1964.

Distribution

Type locality: Washed ashore at Sunday Island, Kermadec Islands, South Pacific. This species is known from the subtropical North Atlantic and the Southwestern Pacific (Nesis, 1982/87).

Other Names for Lampadioteuthis megaleia Berry, 1916

• Lampadioteuthinae Berry 1916
• Lampadioteuthis Berry 1916

References

Nesis, K. N. 1982/87. Abridged key to the cephalopod mollusks of the world's ocean. 385,ii pp. Light and Food Industry Publishing House, Moscow. (In Russian.). Translated into English by B. S. Levitov, ed. by L. A. Burgess (1987), Cephalopods of the world. T. F. H. Publications, Neptune City, NJ, 351pp.

Toll, R.B. 1982. The comparative morphology of the gladius in the Order Teuthoidea (Mollusca: Cephalopoda) in relation to systematics and phylogeny. PhD. Dissertation, University of Miami, 390 pp.

Voss, G. L. 1962. A monograph of the Cephalopoda of the North Atlantic. I. The Family Lycoteuthidae. Bull. Mar. Sci. Gulf Carib. 12: 264-305.

Young, R.E. 1964. A note on three specimens of the squid, Lampadioteuthis megaleia Berry, 1916 (Cephalopoda:Oegopsida) from the Atlantic Ocean, with a description of the male. Bull. Mar. Sci. Gulf Carib., 14(3):444-452.